Three samples of activated carbons of various origins were used in this study. The initial samples were oxidized with nitric acid to introduce oxygen-containing groups. The surface of sorbents was characterized using sorption of nitrogen, Boehm and potentiometric titrations, DRIFTS, and thermal anal
Study of Water Adsorption on Activated Carbons with Different Degrees of Surface Oxidation
โ Scribed by Issa I. Salame; Teresa J. Bandosz
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 119 KB
- Volume
- 210
- Category
- Article
- ISSN
- 0021-9797
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โฆ Synopsis
A carbon of wood origin was oxidized with different oxidizing agents (nitric acid, hydrogen peroxide, and ammonium persulfate). The microstructural properties of the starting material and the oxidized samples were characterized using sorption of nitrogen. The surface acidity was determined using Boehm titration and potentiometric titration. The changes in the surface chemistry were also studied by diffuse reflectance FTIR. Water adsorption isotherms were measured at three different temperatures close to ambient (relative pressure from 0.001 to 0.3). From the isotherms the heats of adsorption were calculated using a virial equation. The results indicated that the isosteric heats of water adsorption are affected by the surface heterogeneity only at low surface coverage. In all cases the limiting heat of adsorption was equal to the heat of water condensation (45 kJ/mol).
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